Alternative energies are becoming ever more important. The problem with alternative energies, e.g., solar or wind power, is that it is not possible to manipulate the times during which energy is generated and surplus energy has to be temporarily stored in order to be available at times when no energy can be generated. It is therefore necessary to use energy storage systems. However, energy storage systems are subject to losses, which should be avoided.
A suitable energy store is a flow battery or an electrochemical energy converter for a flow battery, in particular a redox flow battery, comprising a circulation arrangement for electrolytes, electrolyte lines for supplying and conducting away one or more electrolytes from a supply tank to the electrochemical energy converter and back to the same supply tank in the form of a loop process, the electrochemical energy converter comprising at least one reaction cell having two electrodes and an ion-conducting membrane, preferably a plurality of electrically interconnected individual cells, said cells preferably being supplied with electrolytes in a parallel circuit and each comprising an inlet region for introducing the electrolytes into the reaction cell and an outlet region for conducting the electrolytes out of the reaction cell. To be able to convert electrical energy into an electrochemical energy store of this kind in a particularly efficient manner, it is necessary to control energy store peripherals, e.g., circulation pumps. The current converter device also has to control the power flow direction.
Conventional energy storage systems comprise a control unit for the energy store peripherals, which attempts to detect the current charge state of the energy store on the basis of various parameters, e.g., current, voltage, flow rate, temperature, pressure of the electrolytes, in order to thus control the energy store peripherals such as the circulation pumps.
Conventional current converter devices operate independently of said control unit and use a voltage converter to convert the voltage from the power grid into a voltage for the energy store in the charging mode and vice versa in the discharging mode. In the process, the current converter device controls the power flow direction of the electrical power in the voltage converter.
Losses often arise because there is insufficient interaction between the control unit controlling the energy store peripherals and the current converter device controlling the power flow direction control.